Mystery Antique Darkroom Equipment

I was clearing out my late father's joinery yard today and stumbled across this, (see slideshow). I had no idea what it is for but my sister remembered asking before. It came out of the School of Art in Cork over 25 years ago, when we were building them a new library inside the existing building, so it's probably over 40 years old. I remember the job; I worked there during my summer holidays on the site as a kid.

My sister recalled my father maintained it was for hanging film and was salvaged from the darkroom, which they sacrificed to make room for the library. So I gave it a try, it is remarkable, and it grips it like a vice. The glass balls are smooth and solid, so relatively heavy.

Anyone seen this arrangement before am I on the right track? Is it a negative hanger?

I am seriously considering cleaning it up and taking it home to my own darkroom, it's so handy.